Amenorrhea is when a woman of childbearing age fails to menstruate. A woman normally menstruates every 23 to 35 days. The part of the brain called the hypothalamus regulates the menstrual cycle. The hypothalamus stimulates the pituitary gland. The pituitary gland lies just below the hypothalamus at the base of the brain. The pituitary gland releases two hormones that regulate the female reproductive cycle. They are luteinizing hormone (LH) and follicle-stimulating hormone (FSH). LH and FSH influence the production of estrogen and progesterone. These hormones control cyclic changes in the lining of the uterus. This includes menstruation. In order for a woman to have regular menstrual cycles, her hypothalamus, pituitary gland, ovaries and uterus must be functioning properly. Her cervix and vagina must also have a normal anatomy.
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